The present invention relates to an ink jet recorder which jets out ink from an ink jet port for recording and, in more particular, to recovery means and method for recovering ink in the ink jet port of the record head in a non-printing area.
The prior art of this type is disclosed in the Unexamined Japanese Patent Application Publication No. Hei. 2-1325.
In an ink jet recorder, when a record head is out of operation and waits at the home position (in a non-printing area), the ink jet nozzle (exactly, an ink jet port thereof) of the record head is covered with a cap to keep the ink from drying, thereby not only preventing the ink jet nozzle from being clogged with the dry ink but also protecting it against dust. Further, when undesirable phenomena such as the clogged ink jet nozzle due to the dry ink, dust adhesion or the like occur, in order to recover the condition of the record head to the normal condition as the need arises, there is provided a recovery device in which a suction pump is connected to the cap, the suction pump is operated to generate a negative pressure on the cap side to thereby discharge the dry ink and adhered dust, which are the causes of the clogged nozzle, into the cap, a flexible tube is connected to the cap, and then the thus discharged ink and dust are collected by the tube.
In a ink jet recorder for color recording, normally, record is carried out in yellow, magenta (red), cyan (blue), and black inks, exclusive record heads are provided for the respective color inks, and caps are provided respectively for the record heads. However, in the ink jet recorder of this type, due to the fact that, when executing a recovery operation, the inks are sucked from all record heads, even the ink requiring no recovery is sucked, which results in the unnecessary or wasteful consumption of the ink.
In order to make up for this drawback, in the above-mentioned publication, there is disclosed means which is disposed on the suction pump side and can be used to select one of two ink communication systems, one of them provided between the black ink head and the capping means and the other between the color ink heads and their respective capping means.
However, in the disclosed ink jet recorder, since all inks are sucked from the color record heads when carrying out the recovery operation, the inks are still consumed wastefully. Also, the mechanisms of the disclosed ink jet recorder are complicated, which makes it difficult to secure the airtight condition of the ink suction passage thereof.
Further, in a process on the way to the capping condition, because the volume of the cap is decreased only slightly, a very small positive pressure is generated within the cap to thereby cause the ink filled up in the jet port of the record head to move back to the ink tank side, which raises a possibility that a print failure can occur when starting a recording operation.
In addition, when the ink flowed from the record head is still retained within the cap, unless it is collected completely, then there arises another possibility. That is, when the flexible or elastic cap is contacted with the record head, the volume of the cap is decreased to thereby generate a positive pressure, while this positive pressure pushes out the ink retained within the cap from an air-communication passage. As a result, not only the neighboring portions of the ink jet recorder can be contaminated but also the air can be pushed in from the ink jet nozzle due to the positive pressure to thereby impair the quality of an image printed on a recording sheet.
The present invention aims at solving the above-mentioned problems found in the conventional ink jet recorder.